1. Field of the Invention
The present invention relates to a simulated sound generator for use in an electric vehicle, that generates artificial sounds which are similar to sounds generated by gasoline-powered automobiles at the time they start, run and are accelerated and decelerated, taking ambient noises into account.
2. Description of the Related Art
Conventional pseudosound generators for electric vehicles as disclosed in Japanese laid-open utility model publications Nos. 56-166701 and 56-171501 produce different alarm sounds when the electric vehicle moves forward and backward, respectively, or produce different alarm sounds corresponding to vehicle speeds of forward and backward movement of the electric vehicle.
The known pseudosound generators have an alarm sound source which comprises a multivibrator for generating a pulsed signal. The pseudosound generators produce different sounds by varying the frequency or duty factor (pulse duration) of pulses generated by the multivibrator.
Therefore, the sounds produced by the known pseudosound generators are relatively simple and hence suitable for use as alarm sounds. The conventional pseudosound generators are, however, not suitable for producing sounds which indicate various operating conditions of the electric vehicle to the driver and other people around the vehicle because the pseudosounds produced by the pseudosound generators are greatly different from those produced by gasoline-powered automobiles.
The gasoline-powered automobiles produce engine sounds when the engine is idling at the time they are at rest, and the electric vehicles make no sounds at the time they are at rest as the electric motor of the power unit is de-energized. Consequently, the gasoline-powered automobiles and the electric vehicles differ widely from each other with respect to the manner in which they produce sounds.